The benefits of helpers: Effects of group and litter size on infant care in tamarins (Saguinus oedipus)

The Callitrichidae (marmosets and tamarins) typically give birth to twins, and infant care is shared by all group members. The potential benefits to callitrichids of having helpers were investigated in a study of 21 captive cotton-top tamarin (Saguinus oedipus) infants, living in groups with two to 12 older members. Time carried and suckled and amount of food received from other family members were recorded for each infant during the first 12 weeks of life. The results showed that infants in larger groups were carried more and received more food than those in smaller groups. Twin infants in larger families were less likely to be on the same carrier. Singleton infants were carried more than twins but did not receive more food. On average, individual caretakers in larger groups carried less and shared less food with infants than those in smaller groups. When parental contributions to care were analyzed, no effects of group size were found on mothers' contributions to carrying or food sharing, but fathers in larger groups both carried infants less and shared less food with them. There appear to be several benefits of a communal rearing system to cotton-top tamarins. 1) Infants may receive more care in larger families, thus increasing their chances of survival. 2) The burden of care is spread over several animals, reducing the costs to a given individual. 3) The parents, particularly fathers, may benefit most from reducing the costs of investing in the present litter and increasing their ability to invest in future litters.     

Predator avoidance behaviour in the buffy-headed marmoset,Callithrix flaviceps

The predator avoidance behaviour of a free-ranging group of buffy-headed marmosets,Callithrix flaviceps, was recorded in detail during the course of a long-term study of behavioural ecology at the Fazenda Montes Claros, southeastern Brazil. Four distinct patterns of predator avoidance behaviour, each with specific vocalisations, were recognised and are described here. The selection and use of sleeping sites by the study group are also described. An analysis of the records indicates that these small monkeys are generally most vulnerable to predation by aerial raptors. Variations in the frequency of alarm calls also indicate that the marmosets tend to be more vigilant at higher levels in the forest and when the leaf cover is less extensive. The implications of group size and social structure for both the evolution and the efficacy of the anti-predator behaviour of marmosets are also discussed.     

Intestinal cryptococcosis in a common marmoset (Callithrix jacchus)

A five-year-old female common marmoset (Callithrix jacchus) died after a one-month clinical course of nonspecific signs. Pathologic findings were acute diffuse fibrinonecrotizing enteritis and granulomatous endolymphangitis of intestinal and mesenteric lymphatic vessels. Both lesions were associated with a marked proliferation of Mayer's mucicarmine-positive, 4 to 15 microm yeasts that were surrounded by a wide clear halo. The infection was probably acquired by oral route. Other findings included moderate multifocal granulomatous and necrotizing hepatitis and mesangial nephropathy. Although the immunological status of this marmoset was unknown, cryptococcosis might induce primary lethal intestinal infections in callitrichids.     

Clinical care and diseases of the common marmoset (Callithrix jacchus)

The common marmoset (Callithrix jacchus) is a small New World primate that is native to eastern Brazil and has been used in biomedical research since the early 1960s. Use of this species for research purposes continues to grow at a rapid pace as they are a viable alternative to other nonhuman primate species. We discuss clinical care, such as preventative medicine, anesthesia, and routine clinical procedures. Important viral, bacterial, parasitic, and gastrointestinal tract diseases are discussed, with relevant details on cause, transmission, pathologic changes, diagnosis, and treatment. Current problems affecting marmoset health and research in the modern vivarium are emphasized.     

Handedness in the common marmoset (Callithrix jacchus)

For about 20 months the development of hand preferences in 21 experimentally naive common marmosets (Callithrix jacchus) was examined in 15 different tests. Test preferences were compared with their spontaneous behavior preferences in such contexts as feeding, grooming, play, and others. In the spontaneous use of the hands, only eight animals showed a significant lateral preference (2 left-handed, 6 right-handed). During the test period, however, the number of handed marmosets increased to 19 (5 left-handed, 14 right-handed). Most of the animals fluctuated considerably in their preference levels, a situation which led to a remarkable test response inconsistency of handedness. When the test situation was changed, complete reversals of handedness were more frequent than weakening or strengthening of a particular preference. The animals' emotions during the test session and environmental variables affected handedness significantly. None of the tested marmosets showed an increase of hand preference from the first to the last test. Our results indicate that Callithrix is ambidextrous rather than handed.     

The selection of marmoset monkeys (Callithrix jacchus) in pharmaceutical toxicology

Prior to controlled clinical trials in human volunteers or patients it is required that novel pharmaceuticals are evaluated for pre-clinical safety in a rodent and a non-rodent ('second') species. In most cases the rodent species used has been the rat and the second species has been the dog or macaque (usually cynomolgus or rhesus) monkey. However, there is an increasing trend within the United Kingdom (UK) pharmaceutical industry to use the common marmoset (Callithrix jacchus) for pre-clinical toxicology programmes. This paper examines the practicality of using the common marmoset (henceforth referred to as 'the marmoset') in toxicological testing and reviews metabolic and pharmacodynamic similarities between this species and humans. It then discusses some of the advantages and disadvantages of the use of this species when compared with two other alternatives to the dog and macaque, namely the ferret and minipig. In particular, the marmoset has clear advantages over the macaque in terms of animal welfare and practicality. There is regulatory acceptance of this species for Investigational New Drug (IND), Clinical Trial Exemption (CTX), New Drug Application (NDA) and Marketing Authorization Application (MAA) registrations. Whilst the dog is likely to be maintained as the primary non-rodent species in toxicology, the marmoset has been, and will likely continue to be, adopted as an additional non-rodent species in pre-clinical toxicology programmes where appropriate.     

Home range of a Geoffroy's marmoset group, Callithrix geoffroyi (Primates, Callitrichidae) in South-eastern Brazil

The home range of one group of the Geoffroy's marmoset (Callithrix geoffroyi) was studied in a fragment of the Atlantic Forest in south-eastern Brazil, between February 1993 and January 1994. The total home range was 23.3 ha and the area used in the dry season was significantly larger than that of the wet season. The smallest distance travelled by group was 480 m/day in May and the longest was 1,980 m/day in March, but with no significant differences between seasons. The total home range used for this species agrees with the ecological grouping of the genus Callithrix proposed by Rylands & Faria (1993) and may be associated with the habitat structure, the limit of the fragment and the inexistence of neighbouring groups.     

The black-tailed marmoset (Callithrix argentata melanura) recorded from paraguay

The black-tailed marmoset (Callithrix argentata melanura) occurs in central-western Brazil and adjacent parts of Bolivia, and is the only member of the genus (Callithrix) to occur naturally outside Brazil. Data presented in this paper extend the range of this marmoset at least 200 km to the southwest into yet another country, Paraguay.     

Interactions between parents and infants,and infants-father separation in the common marmoset (Callithrix jacchus)

The New World monkey,Callithrix jacchus, diversely from most Old World primates, shares infant care among all family members. This paper intends to describe a pattern of infant care in the common marmoset, and to verify if the infant-father separation induces a depression reaction, such as found in other separation studies. In Experiment 1, 11 families (mother, father, and twin newborn infants) ofCallithrix jacchus were observed from 1st to 36th days of infants' life. It was noted that infants were carried most of the time in the beginning of life, and that from the 4th day on this care came mostly from the father. In Experiment 2, nine families were divided in three separation groups (15, 30, and 45 days of infants' life). Each group had a control and two experimental families. Removal of the father was done for three days, beginning at the indicated infants' ages. Results showed that upon removal of the father, the mother assumes the infants' care, and no depression reaction appeared.     

X-ray-induced translocations in marmoset (Callithrix jacchus) stem-cell spermatogonia

The induction of reciprocal translocations in spermatogonial stem cells of marmosets (Callithrix jacchus) was studied after irradiation with different doses of X-rays (50, 100 and 200 rad) via spermatocyte analysis many cell generations later. The obtained results show a dose-effect relationship with clear saturation effects at 200 rad. The recorded frequencies of translocations were much lower than those reported for closely related marmosets (Saguinus fuscicollis and Saguinus oepidus). Possible reasons for this difference are discussed.     

Plasma aminotransferase measurements in the marmoset (Callithrix jacchus)

Plasma aminotransferase values were measured in a large number of samples from male and female marmosets. There were no differences due to age or sex for either AST or ALT. Haemolysis affected values for both enzymes, though the effect on ALT was greater.     

The fertility of daughters in common marmoset (Callithrix jacchus jacchus) family groups

Observations previously made in the field of inter-group mating raised questions concerning the fertility of daughters in family groups and about possible competition between mothers and daughters. To test whether daughters in captive family groups could become pregnant, daughters from four groups were placed with a strange male for a period of 30 min, twice a week for eight weeks. No changes were observed in the mother/daughter interactions during the time in which the daughters were allowed contact with the strange male. Two of the daughters showed signs of ovulation and the male only copulated with these animals. One daughter became pregnant, but it was aggression with her siblings rather than her mother which necessitated removing her from her family group.     

Dental development in the cotton ear marmoset (Callithrix jacchus)

The frequency of minutia types was studied in finger prints of 77 males and 82 females. Dermal ridges were clearly printed by a revised method for this purpose. The fork index, which represents the frequency of forks in minutiae, is higher in females for each finger than in males. It differs on each finger, i.e., low on the digit I, high on the digits, III, IV and V, and intermediate on the digit II. The mean of the index for each finger distributes from about 15 to 24. Bilateral difference is not evident. The correlation coefficient between right and left hands ranges from 0.52 to 0.79. Forks appear more frequently in ulnar loops than in whorls. It is revealed that the occurrence of forks differs in dermal regions.